Small toolbar icons not diplaying correctly in FF8

I recently upgraded from Firefox 7 to version 8. Since the upgrade, if I'm using the Default theme and set the toolbar to use small icons, instead of the usual dark-shaded icons I get unshaded white ones. The icons are plain white with single-pixel-width black borders and internal details. They are very bland, and, frankly, ugly. This only happens with the Default (Strata) theme, and ONLY if the toolbar is using SMALL icons. If I go into the customize toolbar dialog and uncheck "use small icons", I get the normal Strata icons again. And if I switch to a different theme altogether, I get that theme's icons, naturally. Are these small icons a "new look" for the Default theme? If so, I'd rather have the old ones back. EDIT: I just realized, the "white icons" only appear if the toolbar's "Tabs on top" property is UNCHECKED. If I re-check it to move the toolbar below the tabs, I get the shaded icons back. Uncheck it again, and the white icons return. I've tried restarting Firefox in Safe Mode, by the way, and get this same behavior. I'm beginning to think this is by design...